My HK-1-8-80A ESC arrived today and I wasted no time tearing it to pieces to see how it's all connected. Turns out there are 3 separate power rails in there:
1. 6V BEC (also powers the cooling fan)

2. 5V from a 7805 to run the micro (input is in fact direct from the battery rather than the 10V rail as previously supposed)

3. ~10V FET gate voltage

I2C pins have FETs attached to them so talking to this controller by I2C is not an option. Fortunately this ESC follows the standard scheme of having the UART pins diode-ORed with the servo input so you can connect a programming card so I should be able to talk serial to it from the "brain" in my walker.

I also noticed that the IRS2003 half bridge drivers that sit between the micro and the FETs prevent you from switching on the high and low FET simultaneously, which makes it much harder to cook the power stage during firmware development. Also the IRS2003 takes care of dead time which I expect will significantly simplify driving the power stage. The SimonK firmware is full of all kinds of complicated stuff for handling dead time in software, because it wants to run on many different ESCs. None of that seems to be required on this ESC.

I'm liking this ESC so far, though it is bigger and heavier than a TZ85A. It looks physically and electrically pretty rugged.

Wed Jun 21, 2017 10:30 pm

Ondray

Joined: 06 Jul 2015
Posts: 127
Location: Newcastle

Here's me just using the HK 100A car ESC as a brushless drive for my weapon motor.

Thu Jun 22, 2017 6:08 pm

chunkulator

Joined: 27 Jul 2016
Posts: 211

Indeed. That's a great solution for a weapon where the startup characteristics and low speed performance don't matter. Doesn't work that well for drive systems, especially if you want to use big honking low kV motors with low gearing.